


Forbidden Sisters

by SansryaFangirl



Category: Supergirl (TV 2015)
Genre: Adopted Sibling Relationship, Alex Danvers is a Gay Mess, F/F, Lesbian Kara Danvers, Pseudo-Incest, Sister/Sister Incest, Vaginal Fingering
Language: English
Status: Completed
Published: 2018-05-13
Updated: 2018-05-13
Packaged: 2019-05-06 01:23:25
Rating: Explicit
Warnings: Underage
Chapters: 2
Words: 2,463
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/14631150
Author URL: https://archiveofourown.org/users/SansryaFangirl/pseuds/SansryaFangirl
Summary: Alex remembers taking Kara's first kiss. Then in the present day, Kara wants another kiss.Alex POV





	1. Chapter 1

Many years ago in the Danvers household. 

Child Kara was hugging young Alex when she suddenly asked, "Alex, how do humans show affection?""

"You mean besides hugging?" Alex giggled. 

"Yes. I am referring to....deeper affection."

"Romantic...?"

"Yes."

Alex thought for a moment. "I see Mom and Dad kiss each other sometimes."

Kara looked at her curiously. "What is kissing?"

Alex inwardly groaned. "I'm gonna have to show you aren't I? Alright....close your eyes Kara."

She slowly leaned in and softly pressed her lips up against Kara's mouth. It was several seconds before she pulled back but the feeling was electric and nothing compared to all the sloppy kisses from guys she had received. She had no idea why.

"Um...Alex that was very nice. Thank you for showing me what kissing is."

"Yeah it was....good." Alex said breathlessly. 

"What else do people on this planet do?"

"I heard in school that they have sex."

There was silence for a long moment.

Then Kara asked, "Can you show me how to have se-"

"NOO!"

 

_Present day._

"If those potstickers are not in my mouth in the next two seconds, Alex, I will send Lena after you." Now that was a threat, Alex thought. Pissed off Lena would destroy anyone who messed with her best friend.

"Promises, promises." Kara warmly smiled at her. Then she suddenly turned serious.

"I should not have introduced you to these when we were kids. It;s too bad you can't get fat."

"Rao, I was so naive when we were kids. Remember when I actually kissed you on the lips?"

"I try not to, Kara! That's so gross!"

"Yeah but....you liked it, right?" Kara grinned. 

"You're my sister, Kara."

"That's not a problem on Krypton."

"You basically have test tube babies! You're a test tube baby."

"We still practice marriages. I could have been promised to Clark had it not exploded."

"Woah Kara...you never told me that."

"It's never had a reason to come up."

"You like Clark?"

"Noooo! It was just an example of an arranged marriage."

"Like Mon El and Imra?"

"Well yes, something like that. To unite the families."

"On Earth we did it for a while, but only in the top royal families, too powerful to be told to stop."

"So....you don't wanna kiss me, Alex?" Kara teased.

"Nooo! Kara.. you're my baby sister!" Alex balked.

"Not even a little biiit?" she continued to tease.

"Wherés this coming from?"

"You once said people who love each other kiss!"

"I don't kiss you?"

"Not like...actual couples are meant to." Alex just stared at her like she had grown three heads. 

"This isn't krypton. We're not gonna be set to marry. We marry who we love."

"Come on, just one kiss! Alex, it won't kill you."

"Are you this lonely and depressed about Mon-El that you're gonna hit on your own sister? Kara, stop it!" Despite her protesting, Alex actually had deeper feelings for her adopted sister when they were younger. They were subtle and deep down but she assumed it was just sisterly over-protectiveness. Then she dated Maggie and while all of Maggie's kisses were great, they never felt like her first kiss with Kara. 

"Wé're not blood related! And no, if anything, being free of him is great for me!"

Ugh...Alex groaned, "This is really wrong but....if it will make you shut up and leave me alone, fine. One kiss."

Kara grinned and leaned in, cupping Alex's cheek and then their lips met. Kara kissed far more softly and gently than anyone Alex had ever known. Kara thought the same thing about Alex. This was why she wanted to kiss Alex again. A deep fire awoke in both of them, as the kiss got more heated and passionate. 

Suddenly Alex pulled back. "I-Im so sorry, Kara. I got carried away."

"It's ok! That was amazing!"

"It's a mistake-"

"You felt it too. We connected."

"....I know. On a level neither of us have with anybody. What do we do?" Alex despaired.

"On Krypton they would have married us but...how about we kiss again?"

"No!"

"Listen, Alex, I've fallen in love with you! There is no one who's been more there for me, or more devoted to me. I know you have feelings for me. Let them out. It's ok." Kara emotionally confessed.

Alex stammered in protest but Kara gave her best soft girlfriend-eyes and she melted. "How are you so fucking cute? Come here."

Kara's tongue pressed against her sister's mouth and Alex let her in. She rubbed and massaged Kara's breasts, making the blonde moan in pleasure. The grinding and kissing increased in pace, with Alex moaning softly. 

"Kara.....Kara! Just give it to me, Kara! I love you so much!"

"I love you, sis!"

Kara's hand slipped down Alex's pants and found her wet tight pussy. She slipped a finger in and began fingerfucking her big sister. 

"Fuck, Kara! Harder!"

Kara lightly bit down on Alex's neck. _I'm finally making love to my amazing, sexy sister! Oh my god, Kara!_

"Fingerfuck your sister! Oh Kara, you're fucking me so good." 

For Alex, Kara had always been that forbidden fruit. It terrified her she had developed an electric feeling around the girl, and desperately buried it away. It was not until her feelings for Maggie that she began comparing them to what she felt for Kara, and realized to her horror they were incredibly similar. She once again buried the feelings away before anything bad happened, sickened and terrified. But Kara pressuring and then seducing her was too much and now those feelings were out. She loved, no, was _in love_ with her own sister. 

Alex's pussy tensed and pulsed, and cum finally began flooding out onto Kara's hand, wetting her panties and jeans. 

"KARAAAA!" Kara giggled, delighting in seeing Alex cum. ,

"Hi hi! You cumming is soo beautiful, sis."

"I love you, Kara!"

"I love you too, Alex."

 

After a long night of hard lovemaking, Alex finally awoke, but Kara was not with her. She yawned, and waited a second but Kara did not appear. She wanted to cry. Was she just a pity fuck?

Then Kara walked in, carrying breakfast. "Finally, sleepyhead! Here is breakfast, Alex." A wave of relief washed over Alex. _I will never doubt you again, my beautiful Kara!_

"Oh god...Kara. You are really the perfect girlfriend."

Kara goofily smiled. "I'm your girlfriend?"

"Of course you are, Kara."

Kara gave her a chaste kiss on the lips. "Now come on, eat up! We got a long day of fucking to do."

Alex smiled in spite of herself. Making love to Kara had been mindblowing, and the best sex she had ever had. She couldn't help but notice Kara being as gentle as possible. She inwardly Aw'd at her sister being so caring and loving. She truly did love Alex.  Alex began to slightly panic at the thought of anyone finding out about their new relationship. Their newfound love would likely not be very accepted by their friends and family but come what may, Kara would always be there for her.


	2. Chapter 2

**Summary for the Chapter:**

> The secret gets out

"UHH KARA! FUCK! FUCK ME HARDER!"

Over the next week, Kara and Alex made love every day, sometimes several times a day. Kara was amazed at the feeling of her sister's tight pussy, and ass. She always licked her fingers after Alex cummed all over them. Alex knew Kara vastly held back to avoid hurting her and blushed at how sweet she was.  _Oh Kara, I love you._

Everything out in the open and finally having no secrets between them proved to strengthen their bond, even though they had become both sisters and lovers. 

Kara then jumped her, pulled off Alex's pants, then put her hand down her panties, finding both her pussy and bumhole, and began fingerfucking her girlfriend hard. 

Alex was in absolute heaven, as her sexy blonde sister ravished her tight holes. She kissed Kara's breasts and suckled on  her nipples. Kara arched her head back and moaned. "Oh Alex, there."

She picked up the pace, clearly enjoying the delightful sounds she was making Alex make. 

"Oh god, Kara, your finger's right up my ass!" Alex screamed.

"I love my sister, Alex. I love my lover. I love my girlfriend. I love my best friend. You're all of them at once to me." Kara emotionally announced.

"KARA YES, FUCK-" Alex screamed.

There was suddenly a rapping at the door. Instantly, the sisters became terrified the arrival had heard them, or at least heard something. 

It was James, who had, given his expression at seeing both Kara and Alex in just bras and panties. 

"Kara? And Ale.....what's...going on here?"

"Oh I don't know James, why are you here?"

"I was going to ask Kara to- You know what? It doesn't matter. You're clearly busy."

"Hey, you obviously have a problem with this! Give it to me, rather than run away."

"You're banging your _sister_ , Kara!"

"I'm not even from this planet, _James_! I think I can make my own decisions on who to sleep with!"

"You know what? This is just- its too weird. I'm gonna go."

He walked off, as Kara fumed. 

"Are they all gonna be like this about you, Alex? Some friends they are!"

"Look, Kara, you're a hero to so many people. Like you said, you're not even human so they can shove their moral objections where you just shoved your hand."

Kara laughed softly, and kissed her sister on the lips softly. 

"I don't deserve you..."

"You do, Kara. I love you."

Just then their phones rang. Looks like this wasn't going to stay secret....Time to face the music. 

First was Lena. 

"Hello Kara. How are you?"

"Lena! I take it you....heard."

"I have experienced scorn all my life for being who I am. Kara. I will not judge my best friend for loving who she loves." 

Kara and Alex almost began to cry. "That means so much, Lena! Thank you!"

"It's ok, Kara. I admit I am a little jealous of Alex, but I'll get over it."

"That really means alot, Lena." Suddenly they had hope not everyone would be as much of a knobhead as James.

 

At the DEO they caught reproachful looks. J'onn however said "Congratulations, girls."

"How did you-"

"I'm psychic, Alex." Alex bushed. _Of course._

They both gave their space-father a hug. 

"It was not my place to say anything, and certainly not my place to judge. Just don't break Alex's heart." 

"I won't!" Kara vowed.

Someone however said in the background, "Sister-fucker."

Kara and Alex scowled. Alex knew she would get this from people but it still hurt. 

Winn said "Hey guys, uh....enjoying the new suit, Alex?"

"Yes, thank you Winn."

"Have you guys..."

"Alot!" _Kara, you don't have to be so direct_ , Alex blushed. 

"I....see.." Winn said, frowning. "Just....don't kiss or anything in front of me." he said as he looked a bit sickened.

 _Another knobhead!_ "Oh we won't, jerk."

They both stomped off.

"I thought Winn would accept us!"

"I only need you, Kara."

"I know, babe."

They kissed right in the middle of the DEO without a care in the world. The rest of the world was just going to have to deal with it, even with headlines at CatCo called

 

_"Exclusive: Drama in the Danvers household. Sisters engage in debauched affair."_

 

"People really don't understand the non blood related thing." Kara raged. "Why is it any of their business? At least Lena's in my corner."

"She's dealt with shit like this all her life, Kar. She wouldn't judge others based on arbitrary norms."

Sure enough, Lena came to their apartment and expressed her support, giving them both a hug after social media exploded with cyberbullying and hate on the sisters. 

"It's no one's place to judge. I'm sorry about them, Kara."

"I love Alex and I think I always have, deep down. I'm just happy to finally have her."

Lena smiled warmly. "That's amazing. Alex you better not break this poor girl's heart or you'll have to deal with me." Alex feared few things. She feared Lena's revenge. 

She gave a small smile and said "I promise I won't."

"Have you guys thought about..."

"Running? I don't want to run, Lena." Kara replied. "It's perfectly legal on this planet to bang your adopted sister. I only came to the Danvers when I was already a young teenager."

"Oh is that right? So you didn't even actually grow up together?"

"Nope!"

"You've been a great friend to us Lena. Thank you so much."

Lena smiled and said "Any time, Alex. I'm needed at the office. I will talk to you later, girls."

 

Cat was next. 

"Keeeera. Finally you answer the phone. Why did you not tell me you were an incestuous lesbian? I expected better-"

Alex grabbed the phone away, "Listen you evil, awful hag! She expected better from you than to be a judgemental hag! Never call us again unless you can accept me being with Kara! I love her, deal with it."

Kara moaned "I'm so hot for you, sis."

Alex grinned and kissed her. They expected the scorn. They expected that. However, it only made them grow closer, and exposed false friends for being false after all. 

The sisters made love like their bodies belonged together. They fit together perfectly. Alex tonguefucked Kara, lapping at her beautiful lovely juices, and amazed at Kara's sounds of pleasure. 

"ALEX...OH RAO, ALEX. I LOVE YOU. RIGHT THERE. FUCK, RIGHT THERE." she screamed in ecstasy. Alex slid in two fingers into Kara's tight pussy.

"Fuck, Alex, fuck me. Suck on my clit. You know I'm your sexy baby sister who needs it. Harder! I'm-I'm cumming! I'm fucking cumming, sis!"

Alex happily drank her little sister's cum, then crawled up and passionately kissed her. _Definitely going to fuck Kara all night._

 

5 years later. 

Kara and Alex had been a settled, normalized couple for years. Almost all their friends had apologized and come around to accept them. They bought a real house, they bought a puppy that Kara named Krypto. Even their sex life had not slowed down one bit, as the sisters would make love sometimes every night. One night...

"Marry me..." Kara whispered while cuddling her sister after another night of hard sex.

"...What'd you just say?"

"Will you marry me? Alex, my sister, my girlfriend, my one true love. I want to marry you!"

Alex squealed, "YES, yes of course, Kara! Oh baby sis, I love you so much!"

Krypto barked and jumped onto the bed. Kara cuddled him as she shared a soft kiss with her fiance. 

They were finally truly happy. 


End file.
